It is common practice to use a single two-wheel hand cart for transporting two cylinders, one with oxygen and the other with acetylene, propane or other liquified fuel gas, to the site of the work to be done, be it welding or metal cutting, together with hoses connecting flow control assemblies to an adjustable torch flame. The control assemblies normally include valves and regulators comprising flow rate and pressure gauges. The complexity of the fuel control assembly presents a risk of fuel leakage at any time a manual fuel valve is open. If not detected before igniting the torch, the escaping fuel may be inadvertently ignited, thereby presenting a further risk that the flame generated by the fuel leak may heat the adjacent oxygen cylinder to such an extent that it increases the PSI level higher than an allowable safe pressure level prescribed by the Department of Transportation (DOT), thus triggering a pressure relief valve which adds oxygen to the ambient air. That makes the torch flame burn hotter.
The oxygen cylinder is usually much taller than the fuel cylinder that contains liquified fuel gas. Once the fuel valve on top of the dome of the cylinder is opened, the liquified fuel gas vaporizes and flows under pressure to the control assembly. Consequently, any leak in the control assembly, or at the coupling of the fuel hose to the assembly, could cause leaking fuel to be ignited near the midsection of the oxygen cylinder. To protect the oxygen cylinder from the flame, a single 1/4" steel plate has been experimentally placed as a firewall between the cylinders. However, such a plate was found to be inadequate as a firewall because the heat on one side of the plate will be quickly conducted to and radiated from the other side at such a temperature that the PSI of the oxygen in the adjacent cylinder quickly rises. If the flame is not detected and the manual fuel valve closed in time, the oxygen pressure relief valve will be triggered causing the leaking fuel to produce a hotter flame, after which a greater disaster could ensue. Thus, an object of the present invention is to provide a firewall that will prevent initiation of such a disaster for an extended period to allow ample time to detect the flame and close the manual fuel control valve.